Device for separation of oil, ventilation system, cylinder head cover and internal combustion engine

ABSTRACT

A device for separation of oil droplets and/or oil mist from blow-by gases of an internal combustion engine is described. Also described is a ventilation system for ventilation of the crankcase of an internal combustion engine, a cylinder head cover and an internal combustion engine, which contain such a device.

The present invention relates to a device for separation of oil droplets and/or oil mist from blow-by gases of an internal combustion engine. Furthermore, it relates to a ventilation system for ventilation of the crankcase of an internal combustion engine, a cylinder head cover and an internal combustion engine, which contain such a device.

In the crankcase of an internal combustion engine, blow-by gases occur, which are guided normally, in particular for environmental reasons, into the intake duct of the internal combustion engine. It must thereby be ensured that the pressure applied in the crankcase is maintained within the narrow required upper and lower limiting values. For this purpose, the blow-by gases are discharged out of the crankcase via a ventilation pipe, for which purpose the pressure difference between the crankcase and the intake duct of the internal combustion engine is used.

A ventilation system for a crankcase for transporting blow-by gases therefore normally has a ventilation pipe from the crankcase to the intake duct of an internal combustion engine. In the ventilation pipe, generally an oil separator/oil mist separator is disposed furthermore in order to separate oil and oil mist, which are contained in the blow-by gases, from the blow-by gases. For this separation, likewise the pressure difference between the crankcase and the intake duct is used. This means that the pressure difference between the intake duct and the crankcase is used suitably for flowing through an oil separator/oil mist separator and therefore is likewise subject to certain limits. In particular, the ventilation must be controlled such that, on the one hand, the occurring blow-by gas flows are discharged safely and, on the other hand, the pressure decrease over the oil separator is within an optimum range for efficiency of the oil separation.

In particular in the case of internal combustion engines with supercharger device/compressor, for example a turbocharger or a compressor, and also a throttle valve, different pressure ratios which depend upon the operating state of the internal combustion engine occur in different sections of the intake pipe between the air filter and the inlet valve of the engine for fresh air.

In full load operation, a very high pressure which cannot be used for suctioning out the blow-by gases and ventilation of the crankcase occurs in the intake pipe behind the supercharger device. Only the low pressure which is applied in the so intake pipe between the air filter and the supercharger device can be used for this purpose in full load operation.

In partial load operation or even in coasting operation, an intense low pressure, which can be used advantageously for ventilation of the crankcase, exists in the region between the throttle valve and the inlet valve of the internal combustion engine.

Here, as in the following, there is considered as full load operation of the internal combustion engine, an operation with extensively or completely opened throttle valve and/or an operation with a pressure of 0 to 700 mbar, advantageously of 0 to 400 mbar, in the ventilation pipe connected to the intake pipe behind the throttle valve and/or with a pressure of 0 to −200 mbar, advantageously of 0 to −60 mbar, in the ventilation pipe connected to the intake pipe in front of the supercharger device. As partial load operation, no-load operation or coasting operation, there is denoted, here as in the following, a load operation with extensively (partial load operation) or completely (coasting operation) closed throttle valve or an operation at a pressure of 0 to −900 mbar, advantageously of 0 to −750 mbar, in the ventilation pipe connected to the intake pipe behind the throttle valve, and/or an operation with a pressure of 0 to −150 mbar, advantageously of 0 to −60 mbar, in the ventilation pipe connected to the intake pipe in front of the supercharger device. The pressures should be understood respectively relative to the atmospheric external pressure.

It is therefore normal to split the ventilation pipe from the crankcase to the intake duct into two ventilation partial pipes, one of which opens into the intake duct between the air filter and the supercharger device and the other of which opens into the intake pipe behind the throttle valve between throttle valve and inlet valve of the internal combustion engine. With suitable interconnection of the ventilation pipe, now, on the basis of the low pressure present in different sections of the ventilation pipe in different operating states, the crankcase can be reliably ventilated.

The ventilation pipe between the crankcase and the intake duct normally has, in the common part of the ventilation pipe, an oil coarse separator with which oil droplets and oil mist can be separated roughly. In the ventilation partial pipes which connect the ventilation pipe to the intake pipe in front of or behind the compressor, further oil separators/oil mist separators which contribute to a further improved oil separation can be introduced.

Even in partial load—or coasting operation, the volume flow which must be guided from the crankcase to the intake duct is significant, a very low pressure and hence a high pressure difference between the crankcase and the intake duct being applied in the intake duct behind the compressor. Therefore, in parallel to an oil separator disposed in the pipe to the intake duct in front of the supercharger device, a bypass pipe is provided, which opens in partial load—or coasting operation and enables a gas flow from the intake pipe via the bypass pipe into the ventilation pipe behind the oil separator. This gas flow is discharged again via the pipe which opens into the intake pipe behind the throttle valve. This bypass pipe therefore makes it possible to admix considerable quantities of fresh air into the blow-by gases inversely to the normal flow direction and thus, on the one hand, to reduce the pressure difference between the intake pipe and the crankcase in coasting operation and, on the other hand, to dilute the blow-gas which, in addition to oil, comprises considerable quantities of unconsumed fuel, especially also in coasting operation, and thus to reduce the proportion of toxic materials in the exhaust gas.

This bypass pipe generally requires additional piping and seals and also not inconsiderable constructional space. Often the bypass pipes also comprise valves which are frequently constructed in a complex manner and hence increase the constructional space requirement even further.

It is therefore the object of the present invention to make available a device for separation of oil droplets and/or oil mist from blow-by gases of an internal combustion engine, and also ventilation systems, cylinder head covers and internal combustion engines which contain said blow-by gases, which require fewer individual parts, are easier and more economical to produce and assemble and enable a more compact construction.

This object is achieved by the device for separation of oil droplets and/or oil mist from blow-by gases of an internal combustion engine according to claim 1. Furthermore, this object is achieved by the ventilation system according to claim 12, the cylinder head cover according to claim 13 and the internal combustion engine according to claim 14. Advantageous developments of the present invention are given in the dependent claims.

The device according to the invention for separation of oil droplets and/or oil mist from blow-by gases of an internal combustion engine is inserted as oil separator/oil mist separator, in particular into the ventilation pipe, in particular into the ventilation partial pipe, which opens into the intake pipe in front of the supercharger device. It has a valve for control of the gas flow between both sides of the device, namely a pressure side and a suction side. With an arrangement of this device in a ventilation pipe from a crankcase to an intake pipe of an intake duct of an internal combustion engine, the side orientated towards the crankcase is thereby subsequently termed pressure side and the side orientated towards the intake pipe, suction side, even if, under specific operating conditions of the internal combustion engine, the actual pressure ratios can be completely reversed.

This valve, which has also an oil separation function at the same time, has at least one base plate. The base plate can be configured in one piece or consist of partial plates which are disposed adjacently to each other. The base plate has a first region and a second region disposed to the side of the first region. The first region has at least one, generally a plurality of, first gas passage openings for passage of blow-by gas from the pressure side to the suction side of the valve. One, a plurality of or all of these first gas passage openings can be closed, on the suction side, by a first valve closure, for example a first flexible tongue disposed on the suction side. Via pretension of this valve closure, a minimum pressure difference between the pressure side and the suction side can be set, above which one, a plurality of or all first gas passage openings are uncovered. Also a gradual or continuous opening of the first gas passage openings in succession can be set via a suitable design of the first valve closure.

In the second region, likewise a gas passage opening is disposed, which now however can be closed via a second valve closure disposed on the pressure side. In a state in which the gas passage openings in the first region are opened because of intense low pressure on the suction side, the second gas passage opening in the second region is closed by the second valve closure. This means that the second gas passage opening, together with the second valve closure, forms a non-return valve. Only when, for example in coasting operation of an internal combustion engine, the pressure ratios in the device according to the invention are reversed and a high pressure prevails on the suction side, is gas able to flow from the suction side via the second gas passage opening to the pressure side, although the first valve closure closes the first gas passage openings. The second gas passage opening, together with the second valve closure, therefore forms a bypass valve around the first gas passage openings for coasting operation of the internal combustion engine.

Advantageously, the at least one base plate can be a one-piece component which is produced, for example, in injection moulding technology, from a polymer material, in particular from a possibly fibre-reinforced thermoplastic.

As a result, as further components of the device according to the invention, only for the first valve closure and the second valve closure, both designed respectively for example as flexible tongue, merely respectively one further component, for example the flexible tongue itself, is required. The entire device according to the invention for separation of oil droplets and/or oil mist has therefore very few parts and can therefore be produced and also assembled economically and compactly. In particular for the non-return valve in the second region of the at least one base plate, no additional tubing is required so that the assembly complexity is reduced. Both on the pressure- and on the suction side, only one common chamber is situated abutting against the device according to the invention. These chambers on both sides of the device according to the invention communicate in the case of at least one opened first valve closure with at least one first gas passage opening and, in the case of at least one opened second valve closure, with at least one second gas passage opening. This underlines the simple construction of the device according to the invention.

According to the invention, advantageously one of the first gas passage openings is unclosable, i.e. permanently opened. This gas passage opening forms an emergency passage from the pressure side to the suction side, which ensures, in the case of very intense low pressure on the suction side relative to the pressure side, a minimum gas flow from the pressure side to the suction side. In particular, such an emergency passage is required in order, in the case where the other first gas passage openings freeze in the first region of the base plate, to enable a minimum gas passage for ventilation of the crankcase in full load operation. Alternatively or also additionally, an opening, in particular a slot, can be provided in the wall of at least one gas passage opening, which slot makes it possible that, even with a closed valve closure, gases pass through the relevant gas passage opening.

The optional, first flexible tongues or second flexible tongues according to the invention can respectively have a retaining arm which is mounted flexibly on the valve body, here the base plate, such that the flexible tongue is movable between a first position, in which it closes the first or second gas passage opening covered by it, and a second position, in which it uncovers the first or second gas passage openings covered by it. Advantageously, the flexible tongues are produced, in particular stamped, as sheet metal part, in particular from a spring-tempered steel.

Each of the flexible tongues can furthermore be pretensioned such that, below a predetermined positive pressure difference (for the first flexible tongue between the pressure side and the suction side, and for the second flexible tongue between the suction side and the pressure side), it closes the respective covered first or second gas passage openings and opens them above a predetermined positive pressure difference. For this purpose, the relevant flexible tongue can be preformed, in particular in the region of the at least one retaining arm thereof.

Furthermore, it is possible to configure the first flexible tongue such that it uncovers the first gas passage openings covered by it in succession during opening. As a result of the successive uncovering of the first gas passage openings, the pressure decrease over the base plate which is determined by the total cross-section of all respectively uncovered first gas passage openings, is controlled gradually or quasi-continuously.

The first gas passage openings or the second gas passage opening can have, on the side orientated respectively towards the first valve closure or the second valve closure, a web-shaped edge which protrudes in a wedge-shape from the base plate and extends circumferentially about the respective gas passage opening as support for the first valve closure or the second valve closure. This web-shaped circumferential edge can thereby protrude overall at the same distance circumferentially from the base plate, i.e. be the same height. Alternatively, the edge can also be flattened in the direction of the mounting of the valve closure so that the valve closure comes to lie on the bevelled edge with pretension.

The protruding edge is in principle suitable as support for the respective valve closure and, in addition, forms a seal between the gas passage opening and the valve closure. Alternatively, instead of a circumferential edge, also a circumferential embossing can be inserted in the respective valve closure (for example if the latter is manufactured from a metal sheet), in particular in the respective flexible tongues, in order to form a better seal of the respective gas passage opening by the associated valve closure. As circumferential sealing elements, also coatings both of the base plate and of the valve closure are possible. Alternatively, it is also possible to coat the valve closure in sections or over the entire surface at least on the side orientated towards the gas passage opening. The valve closure can also be manufactured from a precoated metal sheet.

The first gas passage openings in the first region of the base plate have, in addition to their function of controlling the volume flow of the gas throughflow, in particular also the object of separating oil droplets and/or oil mist from the blow-by gases passing through. This is effected, on the one hand, even in the case of gas passage openings which do not have a further special configuration, since a narrowing of the throughflow cross-section is produced there relative to the region in front of or after the gas passage openings and the gas flow is accelerated or is slowed down at the outlet of the gas passage opening. This leads to a separation of oil droplets and/or oil mist situated in the blow-by gas flow. In order to improve the separation performance further, the cross-section of one, of a plurality of or of all of the gas passage openings in the first region can also have a nozzle-shaped design.

Furthermore, it is possible in order to improve the separation performance to dispose, in one, a plurality of or all the first gas passage openings in the first region of the base plate, a guiding geometry. This guiding geometry can serve in particular for the purpose of setting the blow-by gases passing through in a rotational movement about the axial direction/throughflow direction of the respective passage opening.

For this purpose, in at least one of the gas passage openings, a for example helical guiding geometry can be disposed, which sets the throughflowing gases in rotation about the axial direction of the gas passage opening. If the valve body has a plurality of partial base plates, then, on the one hand, guiding geometries can be disposed in the first gas passage openings only in one of the partial base plates. On the other hand, also in first gas passage openings, successively throughflowed regions of the first gas passage openings can however have guiding geometries in partial base plates disposed adjacently to each other, successively disposed guiding geometries in the same first gas passage opening having the same, however preferably opposite, direction of rotation. Furthermore, the throughflow cross-sections can change along the course, in particular widen. The guiding geometries can be designed, in particular as presented in DE 10 2004 037 157 A1 or in DE 20 2014 002 795 U1. The disclosure content of DE 10 2004 037 157 A1 and of DE 20 2014 002 795 U1 is herewith integrated entirely in the present application.

In the case of the device according to the invention, advantageously two or more flexible tongues can be provided in the first region. The flexible tongues can further improve the oil separation as impact separator behind the gas passage openings.

In the case of two or more flexible tongues, these can have a common attachment region for attachment of the flexible tongues to the base plate. By means of a common attachment region, the attachment region can have a smaller design, material can be saved, space can be made available on the base plate for other components of the valve and/or the valve can have a smaller design. A one-part component with a plurality of flexible tongues can be produced particularly easily, in particular stamped, handled and attached.

In a further advantageous embodiment of the invention, at least one of the flexible tongues is attached flexibly to the base plate via at least one retaining arm such that it is movable between a first position in which it closes the covered first gas passage openings, and a second position in which it uncovers the covered first gas passage openings. As a result, a pressure difference between the suction- and the pressure side of the valve can be adjusted quasi-continuously.

At least one of the retaining arms can be attached such that the flexible tongue attached via the retaining arm is movable such that it is removed successively from the at least two first gas passage openings or closes these successively. As a result, the pressure difference and the volume flow between the suction- and the pressure side of the valve can be adjusted more precisely. As a result, the invention makes it possible to operate the oil separator as a function of the volume flow at an operating point with an optimum number of opened/uncovered passage openings.

At least one of the retaining arms can also be attached such that the associated flexible tongue is removed in a tilting movement from at least two gas passage openings or moves towards these. Also as a result, a predetermined pressure difference between a suction- and a pressure side of the valve can be adjusted more precisely.

At least one of the first flexible tongues can also be attached pretensioned such that it only opens the covered first gas passage openings when the pressure difference between the pressure side and the suction side is above a predetermined threshold value. At least one of the second flexible tongues can be attached comparably pretensioned so that it only opens the covered at least one second gas passage opening when the pressure difference between the suction side and the pressure side is above a predetermined threshold value. If a plurality of first flexible tongues is present, then these can be attached with different pretensions and thus open at different pressure differences. The same applies for the situation with a plurality of second flexible tongues. For this purpose, the flexible tongues or the retaining arms thereof and/or attachment regions are deformed specifically before or during use. A particularly simple type of pretensioned construction is produced if the attachment region and/or the flexible tongue come to lie diagonally on the relevant base plate.

A device according to the invention can be configured furthermore such that the first region of the base plate has at least two groups of first gas passage openings which have respectively at least two gas passage openings. In this case, the valve closure can have a number of flexible tongues corresponding to the groups of gas passage openings, each of the flexible tongues being disposed such that gas passage openings of one group are closable at least partially respectively by one of the flexible tongues.

A further advantageous embodiment of the invention provides that two retaining arms are provided for each of the first flexible tongues, which retaining arms extend along two opposite edges of the flexible tongue and enclose between themselves one of the flexible tongues in the positional plane of the flexible tongue, the retaining arms being attached at one of their ends (directly or indirectly) to the base plate and being connected, at their other end, to the flexible tongue, possibly in one piece. In the case of this attachment, the flexible tongue can be removed from the gas passage openings in parallel in the case of a sufficiently high pressure difference and hence all of the covered gas passage openings open at the same time and to the same degree. In other words, when opening the gas passage openings, the spacing between the flexible tongue and the gas passage openings remains essentially constant over the surface area of the flexible tongue. In order that the first flexible tongue is removed evenly from the covered first gas passage openings in this manner, two bending regions or three bending points can be provided. One bending region is situated advantageously in the region of the attachment of the retaining arms to the base plate, i.e. respectively one bending point on each retaining arm. A second bending region is situated advantageously in the region of the one-piece connection between the retaining arms and the flexible tongue. The bending regions extend essentially parallel to each other and possibly parallel to a straight line which connects attachment points of the retaining arms on the base plate to each other.

Preferably, the retaining arms, viewed in radial direction, i.e. directed away from the attachment points of the retaining arms on the base plate, are connected to the flexible tongue behind the last gas passage opening which can be closed by the flexible tongue, possibly in one piece.

In a further embodiment of the invention, at least two of the first gas passage openings, preferably two first gas passage openings covered by different flexible tongues, can have different cross-sections of their inlets and/or their outlets and/or in the centre between their inlets and their outlets, in particular with respect to the cross-sectional area and/or the cross-sectional shape.

The valves or valve closures of devices according to the invention concern passive elements which in fact can possibly be pretensioned but are controlled individually by the pressure ratios. They manage therefore without additional actuators or electrical or magnetic control units or the like.

In the following, some examples of devices according to the invention, ventilation systems according to the invention, cylinder head covers according to the invention and internal combustion engines according to the invention are now given. The same or similar elements are thereby provided with the same or similar reference numbers and therefore the description thereof is possibly not repeated. In the case of the following examples, each of the examples comprises a large number of additional optional, advantageous developments of the present invention. These can respectively also develop the present invention individually and not only in the illustrated combination. In particular, it is also possible to use combinations of such optional advantageous developments from different subsequent examples together for advantageous development of the present invention, without likewise taking into account respectively all further optional, advantageous developments of the present invention according to the respective examples.

There are shown

FIG. 1 an internal combustion engine according to the invention;

FIG. 2 the oil separator of an internal combustion engine according to the invention according to FIG. 1;

FIG. 3 a device according to the invention, as can be used in the oil separator according to FIG. 2 and in the internal combustion engine according to FIG. 1;

FIG. 4 a further example of a separation device according to the invention;

FIG. 5 a further example of a separation device according to the invention;

FIG. 6 a further example of a separation device according to the invention;

FIG. 7 a further example of a separation device according to the invention;

FIG. 8 a further example of a separation device according to the invention; and

FIG. 9 a cross-section through a valve cover/cylinder head cover according to the invention.

In the following, the subsequently listed reference numbers are used consistently:

Reference number Denoted element 1 internal combustion engine 2 crankcase 3 cylinder head 4 cylinder head cover 5 intake manifold 10 intake duct 11 air filter 12 intake pipe 12a, 12b, 12c pipe sections 13 supercharger device 14 throttle valve 15 first output pipe (ventilation pipe section in full load train) 16 second output pipe (ventilation pipe section in partial load train) 20 oil separator (complete device) 21 gas input chamber 22 ventilation pipe (can comprise a coarse oil separator) 23 device for separating in partial load train 24 coarse oil separator 25 gas output chamber in full load section 26 gas output chamber in partial load section 28 device for separation in full load section 30 Valve 35 base plate 35a, 35b partial base plates 36 welded joint 38 first region 39 second region 40, 40a, 40b first gas passage openings 41 wall or webs of the first gas passage openings 42, 42a, 42b guiding geometry, first and second guiding geometry 43 slit in the wall 50 first valve closure 51 flexible tongue 52 embossing, in particular bead 53 through-opening(s) 54 central axis 55 web 56 fixing means 57, 57′ retaining arms 58 first bending position 59 second bending position 60, 60a, 60b second gas passage opening(s) 62 circumferential edge, web 63 moulded sealing element about the second gas passage opening(s) 70 second valve closure 71 flexible tongue 72 embossing, in particular bead 76 fixing means 77 retaining arm(s) 80 housing 81 inlet 82 flow channel 83 impact wall 86 collection basin 87 oil outlet 88 outlet for purified gas

FIG. 1 shows an internal combustion engine as combustion vehicle in schematic cross-section. The internal combustion engine 1 has a crankcase 2, a cylinder head 3 and also a cylinder head cover/valve cover 4. Furthermore, the internal combustion engine 1 has an intake duct 10 with an air filter 11, an intake pipe 12 with pipe sections 12 a, 12 b and 12 c, a supercharger device 13, for example a turbocharger or a compressor, and also a throttle valve 14. The intake pipe 12 leads, with its section 12 a, from the air filter 11 to the supercharger device 13, with its section 12 b from the supercharger device 13 to the throttle valve 14 and, with its section 12 c, from the throttle valve 14 to an intake manifold 5 on the cylinder head 3.

In the drawing, a ventilation pipe 22 which connects the crankcase 2 to an oil separator 20 is illustrated schematically. In the part of the ventilation pipe 22 opening into the oil separator 20, a coarse oil separator 24 can be disposed. Also in other regions of the ventilation pipe, a coarse oil separator can be provided.

The oil separator 20 has a gas input chamber 21 into which the ventilation pipe 22 opens. The ventilation pipe 22 is illustrated in FIG. 1 as integral element, however it can also lead externally from the crankcase to the oil separator 20.

The gas input chamber 21 serves as settling chamber and forms a pre-chamber in the oil separator 20.

The oil separator 20 has, furthermore, a gas output chamber 25, subsequently termed gas output chamber 25 in full load train, and also a gas output chamber 26, subsequently termed gas output chamber 26 in partial load train. Both gas output chambers 25 and 26 are connected to the gas input chamber 21 so that the blow-by gases can flow from the ventilation pipe 22 via the gas input chamber 21 into the gas output chambers 25 and 26.

Between the gas input chamber 21 and the gas output chambers 25 and 26 or at the beginning of the gas output chambers 25 and 26, devices 28 or 23 respectively for separation of oil droplets and oil mist are disposed. These devices 23 and 28 are flowed through by the blow-by gases, starting from the gas input chamber 21, in coasting- or partial load- and full load operation, the oil droplets and oil mist being separated from the throughflowing blow-by gases.

The gas output chamber 25 in full load train is connected via a first output pipe 15 to the section 12 a of the intake pipe 12. It is also possible to design the gas output chamber 25 itself as part of this first output pipe 15. The gas output chamber 26 is connected via a second output pipe 16 to the section 12 c of the intake pipe 12. Here also, the gas output chamber 26 can in fact be designed as part of the second output pipe 16.

The invention now relates essentially to the device 28 for separation of oil droplets/oil mist in full load train as device according to the invention for separation of oil droplets and/or oil mist from blow-by gases.

In this device 28, a valve 30 and a second gas passage opening 60 are disposed spatially adjacently in a base plate 35. The valve 30 is illustrated in the opened state.

FIG. 1 shows here an internal combustion engine 1 according to the invention in a full-load operating state. In full load operation, the supercharger device 13 compresses the fresh air/combustion air flowing in the intake pipe 12 and produces, in the pipe section 12 a, an intense low pressure. In contrast, a high pressure relative to the crankcase prevails in the pipe section 12 c of the intake pipe 12. Correspondingly, the valve 30 between the gas input chamber 21 and the first output pipe 15 or the gas output chamber 25 is opened so that the blow-by gases are suctioned via the gas output chamber 25 and the first output pipe 15 into the pipe section 12 a of the intake duct 10 (see illustrated arrow).

FIG. 2 shows, in partial FIGS. 2A and 2B, the full load operation and the coasting- or partial load operation for the oil separator 20 from FIG. 1. The arrows thereby show the flow direction of gases in the gas output chamber 25.

On both sides of the device according to the invention, respectively only one chamber 21 or 25 is situated, which both communicate with the gas passage openings 40 or 60 in the case of correspondingly opened valve closures 50, 70. The communication is effected directly via the possibly multipart base plate 35 without additional components, tubing or the like.

As described above already, the blow-by gases in FIG. 2A in full load operation flow from the gas input chamber 21 via the valve 30 and the gas output chamber 25 to the first output pipe 15. As can be detected already in FIG. 2A, the device 28 for separation of oil droplets and oil mist in full load train has a base plate 35. In this base plate 35, the valve 30 and the second gas passage opening 60 are disposed adjacently in the positional plane of the plate. The valve 30 has, on the one hand, first gas passage openings 40 between the two sides of the base plate 35. On the suction side of this valve, i.e. on that side on which a low pressure is applied in full load operation, a first valve closure 50 is disposed, which valve closure opens when the negative pressure difference, i.e. the low pressure between the suction side of the base plate 35 (the gas output chamber 25) and the pressure side of the base plate 35 (pre-chamber 21) exceeds a predetermined threshold value. The blow-by gases can flow then through the first gas passage openings 40. Because of the pressure ratios prevailing in the gas passage openings 40 and possibly due to a particular embodiment of the gas passage openings 40, oil (droplets and/or mist) are separated from the blow-by gases in the gas passage openings 40.

The second gas passage opening 60 is provided, on the pressure side of the base plate 35, with a second valve closure 70 which closes the second gas passage opening 60 in full load operation.

Between the pre-chamber 21 and the gas output chamber 26, a device 23 for separation is likewise disposed, through which device however no gases flow from the pre-chamber 21 into the gas output chamber 26 in full load operation because of the pressure ratios between the pre-chamber 21 and the gas output chamber 26.

FIG. 2B shows the same oil separator 20 in the case of partial load- or coasting operation of the internal combustion engine 1. In partial load- or coasting operation, an intense low pressure is applied in the second output pipe 16, which is significantly higher (overall i.e. lower pressure) than the low pressure in the first output pipe 15. Since in partial load- or coasting operation, the low pressure in the crankcase must not become too great and in particular in coasting operation, the blow-by gases comprise a considerable proportion of unconsumed fuel, the oil separator 20 is scoured with fresh air via the first output pipe 15 in partial load- or coasting operation so that dilution of the blow-by gases also takes place. In this case, fresh air now flows from the intake pipe 12 in the section 12 a via the first output pipe 15 into the gas output chamber 25 which here however now forms a gas input chamber for the fresh air. Because of the pressure difference between the gas output chambers 25 and 26, the first valve 30 is closed, whilst the valve closure 70 uncovers the second gas passage opening 60. Now the fresh air can flow via the gas output chamber 25 in the direction of the pre-chamber 21 and can be guided from there, mixed with the blow-by gases, from the ventilation pipe 22 via the oil separator 23, the second gas output chamber 26 in the partial load train and the second output pipe 16 to the section 12 c of the intake pipe 12. By means of the supply of fresh air, the low pressure in the gas input chamber 21 is reduced relative to the crankcase. Hence, too low a pressure in the crankcase is prevented.

FIG. 3 shows a section of an embodiment of the device 28 for separation according to the present invention. FIG. 3A thereby shows a perspective plan view on one side of the base plate 35, FIG. 3B a perspective plan view on the opposite side of the base plate 35 in the case of a closed valve closure 70 and FIG. 3C a plan view on this second side of the base plate 35 in the case of an opened valve closure 70.

The device 28 has a valve 30 in a first region in the base plate 35 thereof. For this valve 30, two groups with respectively eight first gas passage openings 40 are disposed in the base plate 35. These first gas passage openings 40 have webs 41 which extend circumferentially from the base plate 35 in the direction of the suction side of the base plate 35 illustrated in FIG. 3A and which are connected together to form a block which protrudes out of the base plate 35.

On the central axis 54 between these two arrangements of gas passage openings 40, attachment means 56, here pins 56, are disposed, on which two flexible tongues 51 are mounted. These two flexible tongues 51 serve as first valve closures 50 and are thus configured such that they can close respectively all of the first gas passage openings 40 respectively of one block. For mounting on the pins 56, the flexible tongues 51 are connected at the side to a web 55 via retaining arms 57, the web 55 being mounted, for its part, on the pin 56. This arrangement of web 55, retaining arms 57 and flexible tongue 51 is normally produced from a metal, for example a sheet metal. It has two bending points 58 and 59 so that the retaining arms 57, viewed from the surface of the base plate 35, can bend away from this surface. The second bending point 59 makes it possible that the flexible tongue 51 moves parallel to the surface of the respective block of first gas passage openings 40. In FIG. 3A, the flexible tongues 51 are illustrated in an opened state in which a low pressure is applied on the suction side of the base plate 35, i.e. in full load operation. Both flexible tongues 51 open, in this example, at the same pressure difference between the suction side and the pressure side of the base plate 35.

In FIG. 3B, the pressure side of the base plate 35 is illustrated, i.e. the surface of the base plate 35 which is orientated towards the gas input chamber 21. The gas passage openings 40 have walls 41 here also which are connected together to form a block, respectively in groups of eight gas passage openings. The gas passage openings protrude from the base plate 35 also on this side of the base plate 35. By means of this configuration of the gas passage openings 40 on both sides of the base plate 35, a length of the gas passage openings 40 is adjusted so that the flow path of the blow-by gases in the gas passage openings 40 is sufficiently long to separate oil droplets or oil mist therefrom.

On the pressure side of the base plate 35, the second gas passage opening 60 with a circumferential web 62 protrudes from the base plate 35. On the second gas passage opening 60, a second valve closure 70 with a flexible tongue 71 is disposed in addition. The flexible tongue 71 is attached to the base plate 35 by means of an attachment means 76 via a retaining arm 77.

The web 62 has a height which changes circumferentially, as illustrated in FIG. 3C, for the opened state of the second gas passage opening 60. This makes it possible to place the second flexible tongue 71 with pretension in a planar and hence sealing manner on the bevelled circumferential edge of the web 62. A moulded sealing element is applied circumferentially furthermore on the web 62, for example a circumferential coating or a sealing lip made of an elastomer. Consequently, a particularly good seal between the web 62 and the flexible tongue 71 is achieved in the closed state. Alternatively, it is also possible, instead of the circumferential sealing element on the flexible tongue 71, to provide a bead-shaped embossing which protrudes in the direction of the web 62, or another circumferential sealing element, for example a circumferential coating or a sealing lip made of an elastomer.

With sufficient high pressure on the suction side of the base plate 35 relative to the pressure side of the base plate 35 illustrated in FIGS. 3B and 3C, the flexible tongue 71 lifts from the edge of the web 62 and opens the second gas passage opening 60. It is hence possible, in partial load- or coasting operation, to guide fresh air from the section 12 a of the intake pipe 12 into the gas input chamber and thus to limit the low pressure in the crankcase 2 (see FIG. 1).

FIG. 4A and FIG. 4B show a further embodiment of the device for separation according to the invention in perspective plan view on both sides of the base plate 35.

The base plate 35 in this embodiment has two partial base plates 35 a and 35 b which lie directly one upon the other. Whilst in FIG. 3 the gas passage openings and the valve elements are all configured on a single, one-part base plate 35, protruding from the latter in both directions, now the protruding components of the valves are configured respectively for one side on one of the partial base plates 35 a and 35 b. The first gas passage openings which protrude from the partial base plate 35 a are now termed openings 40 a, whilst the first gas passage openings which protrude from the partial base plate 35 b are termed gas passage openings 40 b.

In contrast to the device in FIG. 3, now the first gas passage openings 40 a and 40 b have guiding geometries 42 a, 42 b which direct the gas flow flowing through the first gas passage openings 40 a and 40 b. In FIG. 4, guiding geometries are illustrated, which deflect the gas guided through the gas passage openings 40 a and 40 b in the form of a half right- or left screw. Consequently, the guided-through gases are set in a rotational movement, which reinforces the separation performance of the respective gas passage openings 40 a and 40 b. A particularly high separation performance is achieved if the guiding geometries in the gas passage openings 40 a and 40 b are configured such that the direction of rotation of the gases changes abruptly upon transition from the gas passage openings 40 b to the gas passage openings 40 a. This can be effected by the direction of rotation of the guiding geometries in the gas passage openings 40 a and 40 b for the two base plates 35 a and 35 b being chosen to be in different directions.

FIG. 5 shows, in the partial images 5A to 5E, a further embodiment of the device 28 for separation according to the invention in perspective plan view (FIGS. 5A to 5C) or plan view (FIGS. 5D and 5E) on both sides of the base plate 35. This device is configured extensively like the corresponding device in FIG. 3. The base plate 35 is however not configured in one piece but has two partial base plates 35 a and 35 b, the base plate 35 a covering the base plate 35 b only partially. The first valve 30 is thereby disposed in the base plate 35 a (which indicates the first region 38 of the base plate), whilst the second gas passage opening 60 is situated only in the part of the base plate 35 not covered by the base plate 35 a (which indicates the second region 39 of the base plate). FIG. 5A shows this device 28 in a state in which the first valve 30 is closed by means of the flexible tongues 51 situated on the gas passage openings 40. In FIG. 5B, a state is shown in which merely one of the flexible tongues 51 is lifted from the assigned gas passage openings 40 a and consequently the valve 30 is partially opened. In the case of further increased low pressure on the side of the base plate represented in FIG. 5C, also the second flexible tongue 51 is then lifted from the assigned gas passage openings 40 a and consequently opens the valve 30 completely. Via the configuration of the retaining arms 57 and that of the bending points 58 and 59, consequently a valve opening characteristic for each individual flexible tongue 51 can be adjusted.

In addition to the previously illustrated devices 28, in addition one of the flexible tongues 51 now has a through-opening 53 which is disposed above one of the first gas passage openings 40 a. This gas passage opening 40 a assigned to the through-opening 53 cannot therefore be closed by the assigned flexible tongue 51 so that a minimal gas passage through the valve 30 is ensured.

As can be recognized in FIG. 5C, the gas passage openings 40 a of one block have the above-described guiding geometries. In contrast, the gas passage openings 40 a of the other block have no such guiding geometries.

FIGS. 5D and 5E now show the surface of the partial base plate 35 b, the valve closure 70, in FIG. 5D, closing the second gas passage opening 60 completely. In order to ensure a uniform support of the flexible tongue 71 in the closed state of FIG. 5D, the attachment 76 of the flexible tongue 71 is increased via the retaining arms 77, similarly to how the circumferential edge of the passage opening 60 is increased by means of the web 62. In the closed state, the valve closure 70 consequently extends in one plane and the flexible tongue 71 can then in fact lie on the web 62.

In FIG. 5E, the flexible tongue 71 is shown in a state in which it is lifted from the circumferential edge/web 62 of the gas passage opening 60. In this illustration, it can be detected particularly well that the gas passage openings 40 b, in one of the two blocks, have no guiding geometries, whilst they comprise guiding geometries 42 b in the other block. These guiding geometries can be configured as in the previous example.

FIG. 6 shows, in the partial images 6A and 6B, a further embodiment of the device 28 for separation. FIG. 6A shows a plan view on the suction side of the base plate 35 whilst FIG. 6B displays a plan view on the pressure side of the base plate 35.

In this embodiment, a large number of flexible tongues 51 is provided, starting from a central web 55. The central web 55 extends along a central axis 54 and is attached at three places to the base plate 35 by means of attachment means 56. Along this central axis 54, flexible tongues 51 branch off from the central web 55 on both sides and have a widened, circular end. These circular, head-like ends serve similarly to the above examples for closure of gas passage openings 40 situated thereunder. All of the flexible tongues 51 are connected to the central web 55, the entire component connected via the central web is a one-part sheet metal part, in particular made of spring steel.

Because of the varying configuration of the retaining arms which extend between the central web 55 and the circular end of the flexible tongues 51, the opening and closing properties of the respective valve elements can be adjusted individually and a particular opening and closing characteristic of the valve 30 can be produced.

In FIG. 6B, a plan view on the second side of the base plate 35 is illustrated. This shows the passage openings 40 and also the second valve closure 70. The second valve closure 70 is configured as valve tongue 71 which is attached via a retaining arm 77 and an attachment means 76 to the base plate 35. The flexible tongue 71 now has an embossing 72 circumferentially, in particular a bead, for example a half-bead which is z-shaped in cross-section and protrudes out of the flexible tongue 71 in the direction of the base plate 35. This embossing 72 serves as support and sealing element relative to the circumferential edge of the passage opening 60. In the view of the suction side in FIG. 6B, it can be detected further that the passage openings are surrounded, at least on this side, not only by circular raised portions over the surface of the base plate 35 but also raised portions are present on the regions situated opposite the support faces of the retaining arms and the web of FIG. 6A, which raised portions are however responsible exclusively for simplifying the injection moulding production process of the base plate 35.

FIG. 7 shows a further embodiment of the device 28 according to the invention, as is illustrated for example in FIG. 3.

In contrast to FIG. 3, now guiding geometries 42 are disposed in all passage openings 40. In addition, an opening 53 which serves as non-closable bypass for gases in both passage directions is provided in the base plate 35. The further configuration of this embodiment is corresponding to that in FIG. 3.

The flexible tongues 51 have embossings 52, for example beads, which protrude out of the flexible tongues 51 in the direction of the gas passage openings 40. These beads serve, just as in the previous example, as support and sealing elements for the flexible tongue relative to the circumferential edge of the respectively assigned passage openings 41.

Also the flexible tongue 71 is provided with a corresponding embossing 72 in this example.

FIG. 8 shows a further embodiment of the device 28 according to the invention, here only a perspective plan view of the suction side being illustrated. The two first flexible tongues 51 are attached respectively to a first partial base plate 35 only via one retaining arm 57 and one retaining region 56. One of the passage openings 40 which are combined to form a block in the left half of the partial base plate 35 via a common wall has at least one slot 43 which makes it possible that the relevant passage opening 40 enables passage of blow-by gas even with a closed flexible tongue 51, which gas can emerge through in fact this slot 43. The second passage opening 60 is configured in the second partial base plate 35 b. This embodiment differs from the preceding one by both partial base plates 35 a, 35 b extending only over a part of the surface area of the base plate 35 spanned in common by them, said partial base plates being connected together, in their overlapping region, via a weld seam 36, by means of e.g. hot gas-, friction- or ultrasonic welding and thus ensuring the seal of the base plate 35. Alternatively, the two partial base plates 35 a, 35 b could also be glued together at least in surface portions.

FIG. 9 shows a cylinder head cover 4 according to the invention, having a housing 80 characterised with broken lines. In this housing, a flow channel 82 for blow-by gases is disposed. It has a gas inlet 81 which is connected to a ventilation pipe from a crankcase. The gases then flow along this flow channel 82 via impact walls 83 as coarse oil separator and subsequently through a device 28 according to the present invention. After leaving this device 28, the gases flow further towards an outlet 88 for purified blow-by gas which is connected to the intake duct of an internal combustion engine. Behind the device 28, in the gas throughflow direction, a collection basin 86 for separated oil with an oil outlet 87 is disposed. The device 28 has a base plate 35 with two partial base plates 35 a and 35 b in which a valve 30 and a second gas passage opening 60 are provided in the plane of the base plate 35, disposed adjacently. On the side of the partial base plate 35 b, orientated towards the inlet 81, a flexible tongue 71 as second valve closure is provided for the second gas passage opening 60. Furthermore, first gas passage openings 40 a, 40 b which are provided respectively with guiding geometries 42 a or 42 b are situated in the positional plane adjacent to this second passage opening 60. For each (possibly also for a plurality) of gas passage openings 40 a, a flexible tongue 51 which can uncover or close gas passage openings 40 a covered by it is provided. In FIG. 9, a state is illustrated in which one of the gas passage openings 40 a is uncovered and one of the gas passage openings 40 a is closed, as is illustrated for example in FIG. 5B for groups of gas passage openings.

The gas passage openings 40 a and 40 b have guiding geometries 42 a and 42 b which are orientated in opposite directions and with which the passing blow-by gases are set in a rotational movement. In addition, an abrupt change in direction of rotation of the gases takes place during transition from the gas passage openings 40 b to the gas passage openings 40 a, as a result of which an increased oil separation is made possible.

The blow-by gases flowing into the flow channel 82 via the inlet 81 are consequently firstly cleaned roughly of oil via the impact separator 83. Subsequently, they flow through the passage openings 40 b and 40 a and are consequently purified furthermore also of smaller and finer oil droplets and oil mist. The passage openings 40 a and 40 b serve, in cooperation with the flexible tongues 51 and 71, in addition for limiting and controlling the pressure decrease between the crankcase and the intake duct in the full load case. The thus purified gases flow further to the outlet 88 and are guided from there into the section 12 a of the intake pipe 12 in front of the supercharger device 13.

In partial load- and coasting operation, a high pressure is applied at the outlet 88 by fresh air from the section 12 a of the intake duct 10. This can flow via the second gas passage opening 60 in the case of an opened valve tongue 71 into the chamber between the gas inlet 81 and the device 28. From there, this supplied fresh air can be guided into a (in a plane of the valve cover 4 which is different from the drawing plane) partial load train and gas output chamber 26 disposed in the valve cover. 

1-14. (canceled)
 15. A device for separation of oil droplets and/or oil mist from blow-by gases of an internal combustion engine, having a valve for control of the gas flow between a pressure side and a suction side of the device, the valve having at least one base plate, comprising: a first region of the base plate, in which there are disposed at least one first gas passage opening for passage of gas from the pressure side to the suction side of the valve and also, on the suction side of the base plate, at least one first valve closure for suction-side closure of the at least one first gas passage opening, and a second region of the base plate which is disposed sidewards to the first region and in which there are disposed at least one second gas passage opening for passage of gas from the suction side to the pressure side of the valve and also, on the pressure side of the base plate, at least one second valve closure for pressure-side closure of the at least one second gas passage opening.
 16. The device according to claim 15, wherein the first valve closure has at least one first flexible tongue which is disposed on the suction side of the base plate.
 17. The device according to claim 16, wherein the first flexible tongue is configured such that at least one of the first gas passage openings is unclosable by the first flexible tongue.
 18. The device according to claim 17, wherein at least one of the first flexible tongues is attached flexibly to the valve body via at least one retaining arm such that it is movable between a first position, in which it closes the first gas passage openings covered by it, and a second position, in which it uncovers the first gas passage openings covered by it.
 19. The device according to claim 15, wherein the second valve closure has at least one second flexible tongue which is disposed on the pressure side on the base plate and is configured such that at least one of the second gas passage openings is closable by it.
 20. The device according to claim 19, wherein the second flexible tongue is pretensioned such that it closes the second gas passage opening below a predetermined positive pressure difference between the suction side and the pressure side, and opens the second gas passage opening above a predetermined positive pressure difference between the suction side and the pressure side.
 21. The device according to claim 20, wherein at least one of the second gas passage openings as support for the second flexible tongue has on the pressure side of the base plate an edge which protrudes in a web-shape from the base plate and extends circumferentially about the second gas passage opening.
 22. The device according to claim 15, wherein a circumferential edge has circumferentially the same height or is flattened in the direction of the mounting of the second flexible tongue or has an additional sealing element which extends circumferentially on the edge.
 23. The device according to claim 15, wherein at least one of a first or a second flexible tongue has an embossing which extends circumferentially about at least one of the first and/or second gas passage openings.
 24. The device according to claim 23, wherein the embossing is a bead-shaped embossing, or a circumferentially extending sealing element.
 25. The device according to claim 15, wherein at least one of the at least one first gas passage openings has a narrowed cross-section which acts as oil separator element.
 26. The device according to claim 15, wherein in at least one of the at least one first gas passage openings there is disposed a flow-deflection- and -guiding element as an oil separation element.
 27. The device according to claim 26, wherein the element is a screw-shaped element.
 28. A ventilation system for ventilation of the crankcase of an internal combustion engine, comprising: an intake duct with a compressor and a throttle valve, having an oil separator with a gas input chamber and at least two separate gas output chambers connected therewith, a first ventilation pipe for connecting the crankcase of the internal combustion engine and the gas input chamber of the oil separator, a first output pipe for connecting the first gas output chamber to the intake duct of the internal combustion engine before the compressor, and a second output pipe for connecting the second output chamber to the intake duct of the internal combustion engine behind the throttle valve, wherein in the first output chamber, there is disposed a device for separation of oil droplets and/or oil mist. 